A type of vehicle with three wheels, Tricycles can either be powered by an engine (motortrike) or by pedals. A tricycle can have two wheels at the back and one at the front (frog) or two wheels at the front and one at the back (tadpole).
Pedal tricycles can either be upright much like a common bicycle or can be recumbent. Most upright tricycles tend to have have two wheels at the back (frog) where as the recumbent variety more commonly have two wheels at the front (tadpole).